1. Field of the Invention
The present invention relates to a multilayer substrate, and more particularly relates to a multilayer substrate including a ground conductor and a signal wire.
2. Description of the Related Art
As an example of existing multilayer substrates, a flexible printed substrate disclosed in Japanese Unexamined Patent Application Publication No. 2006-165079 is known. FIGS. 5A and 5B illustrate the configuration of a flexible printed substrate 500 disclosed in Japanese Unexamined Patent Application Publication No. 2006-165079.
The flexible printed substrate 500 includes a composite sheet 502 and a metal plate 504 as illustrated in FIG. 5A. The composite sheet 502 includes a plurality of stacked insulating sheets and has a conductor pattern (not shown) in the composite sheet 502. The metal plate 504 is provided in the composite sheet 502. The above-described flexible printed substrate 500 is bent along a chain line 506 shown in FIG. 5A. During bending, the metal plate 504 is plastically deformed such that the flexible printed substrate 500 retains a folded state illustrated in FIG. 5B. Accordingly, the flexible printed substrate 500 can be used in the folded state.
When the metal plate 504 and the conductor pattern are close to each other, a stray capacitance may be formed between the metal plate 504 and the conductor pattern in the flexible printed substrate 500. As a consequence, electrical characteristic values of the flexible printed substrate 500 may often deviate from desired values.